1. Field of the Invention
This invention pertains to a lightweight, compact apparatus, referred to as a deadend used to attach aerial fiber optic transmission, ground wire or conductor cables to support structures such as poles or towers. Specifically, this invention relates to a deadend that has a body that holds multiple wedges which form an opening for receiving cable.
2. Technology Review
Existing deadends are generally bulky and difficult to install. Several different types of deadend technology are presently used for joining aerial fiber optic transmission, ground wire or conductor cables to support structures. One type of deadend widely used is the formed wire deadend shown in FIG. 1. These deadends consist of bundles of wires joined side by side and formed into a helical ribbon. Three to four of these bundles are wrapped around the cable side by side to virtually surround the cable. A second layer of formed wires are wrapped over this inner layer. This second layer has a formed bail or attaching cable which is placed over a thimble clevis attached to the support structure.
The formed wire deadend is difficult to install. For example, wrapping the formed wires around the cable requires a great deal of hand strength. Also, the installer""s fingers often get pinched while wrapping the formed wires around the cable. Further, these deadends can be as long as twelve feet and are heavy and bulky, and therefore, cannot be installed from the support structure. Also accurate alignment, which often takes a great amount of time, must be maintained between the bundles of formed wires.
A second type of deadend, shown in FIG. 2 is a deadend in which wire retaining rods, similar to the formed wire deadend described above, are wrapped about and surround the cable. A housing with wedges is placed about the wire rods and the cable sits within a groove formed by the wedges. The cable is gripped by the wedges as they are moved forward and squeeze the cable. Many of the problems associated with the formed wire deadend are also associated with this deadend.
Bolted deadends, as shown in FIGS. 3 and 4, are other types of deadend currently used. These deadends consist of a base plate with a groove sized to fit a specified cable design and cannot be easily adapted to accommodate various sized cables. A series of plates with matching grooves are bolted onto the top of the base plate with the cable sandwiched between. Bolted deadends are typically used for large cables and cables carrying very high cable loads. Again, this type of deadend is very heavy. Further, because of the numerous bolts that must be tightened, the bolted deadend is difficult and time-consuming to install.
Applicant teaches a deadend for ADSS cable which is compact, lightweight and inexpensive to manufacture in U.S. Pat. 5,647,046. This deadend, which is easy to install, meets the system performance requirements of strength and long term reliability without deteriorating cable performance and can be installed from the support structure. There is, however, a need for a deadend for optical ground wire (OPT-GW) cable that is also compact, lightweight and inexpensive to manufacture. It is desirable that this deadend also be easy to install and meet all system performance requirements of strength and long term reliability required of OPT-GW deadends without deteriorating cable performance. Further, the deadend should be capable of being installed from the support structure.
It is an object of the present invention to provide a deadend for joining aerial fiber optic transmission, ground wire or conductor cables to support structures that is inexpensive and easy to install.
It is another object of the present invention to provide a deadend for joining aerial fiber optic transmission, ground wire or conductor cables to support structures that is compact and lightweight.
It is a further object of the present invention to provide a deadend that can accommodate cables of different sizes.
It is still a further object of the present invention to provide a deadend that is capable of being used on different types of cable construction.
It is yet another object of the present invention to provide a deadend for joining aerial fiber optic transmission, ground wire or conductor cables to support structures that is easy, fast and safe to install and does not require special tools for installation.
It is still another object of the present invention to provide a deadend for joining aerial fiber optic transmission, ground wire or conductor cables to support structures that meets the system performance requirements of strength and long term reliability without deteriorating cable performance.
Additional objects and advantages of the invention will be set forth in the description that follows.
This invention is directed to a deadend device, called a wedge deadend, employed to attach aerial fiber optic transmission, ground wire or conductor cables to support structures such as poles or towers. The wedge deadend has a body with an attachment eye for mounting the deadend to a support structure. The body accommodates multiple interlocking wedges. The wedges track the inside of the body and interlock with each other via teeth. When the body is closed, the wedges form an opening through which cable can be strung. An elastomer nose bushing may be used to cushion the cable or conductor from abrasion at the span end of the body.
The body consists of multiple hinged segments that are opened and closed to load and access cable. The body hinges are incorporated onto the body segments using a method of casting which will eliminate the need for machining. The body segments are tapered such that one end of the body when closed is angled inwardly. The wedges are similarly tapered enabling them to be interlocked with the body segments. The wedges also have a groove that is sized and textured to grip cables of various range diameters. The wedges are designed to compress the encased cable evenly along the entire contact surface of the cable.
The deadend is installed by hand by opening the body, shifting the wedges toward the attachment eye end of the body, aligning the ends of the wedges and then placing the cable inside the wedges located in a portion of the body. The body is then closed such that the wedges located in the upper portion of the body complete the encasement of the cable. A securing fastener is used to maintain the body closed. The tension and the weight of the cable advances the wedges forward toward the span end of the body to provide a grip force about the cable that is proportional to the cable pull. The taper of the body and the corresponding taper of the wedges make the deadend self-loading when cable pull is applied. This taper prevents the wedges from backing and loosing the grip about the cable. Finally, the attachment eye is attached to the support structure.